1. Technical Field
The invention relates to the irrigation of crops. More particularly, the invention relates to a portable irrigation system.
2. Description of the Prior Art
Sprinkler irrigation has over the years replaced many other forms of irrigation methods because it minimizes erosion, prevents many drainage problems, does not require land leveling, and generally provides a uniform application of moisture to irrigate crops on a variety of terrains and minimal management expertise.
Sprinkler irrigation systems are typically classified by the degree of their portability. For example, there are permanent systems, fully portable systems which can be moved from one field to another, and semi-portable systems which move through the field mechanically but are cumbersome to move to different locations.
Portable irrigation pipe has been an integral component of irrigation systems in the western United States for over fifty years. Portable piping used outside of agriculture for emergency response, waste water spray fields, dust control, and temporary pipelines provides an essential tool and solution for construction, public works, and pollution control.
Aluminum pipe having brass impact sprinklers for solid set irrigation is the dominant choice for overhead irrigation and seed germination in the western United States. Portable aluminum pipe is also used for drip main lines and surface irrigation systems. It is the common experience of those who use such state of the art irrigation systems that the systems are subject to damage and corrosion, and are unreliable, have less than reliable coupling devices, they leak, they commonly exhibit unsatisfactory sprinkler water distribution, have high labor and maintenance requirements throughout operation, and safety issues such as electrocution and back injuries are common. Further, portable aluminum pipe systems must be moved or removed by hand to facilitate the cultural operations which are common to farming, i.e. cultivating, fertilizing, spraying, bed shaping, planting, and harvesting.
One solution to the shortcomings of such portable irrigation systems is to provide aluminum or PVC mains to transport water and nutrients to a manifold system of small diameter pipe or hose and drip tubes (drip irrigation system). Drip systems by nature are best operated on a crop demand basis and require frequent matching of evapotranspiration. The frequency of irrigation with correct timing and a program of injecting nutrients results in conservation of water and fertilizer and typically excellent yields. Drip systems are difficult to design and install, subject to plugging, often do not germinate seeds well, require intensive management supervision and do not lend themselves to difficult terrain; they are expensive to install and disposal of thin wall drip tubing (which lasts from one to five years) is prohibited in certain areas and expensive.
One solution to the undesirable drain and leaky gasket problem (in the case of aluminum pipe) is the installation of a watertight gasket. However, the use of a watertight gasket creates a second, more serious problem. Aluminum pipe couplers are designed to drain at low pressure to enhance portability. Given that non drain gasket would no longer drain the water, fertilizer, acid, and chlorine combination that growers inject into the lines to disperse nutrients and to prevent clogging, there is a greater opportunity for such combination of chemicals to corrode the pipe.
One solution to the corrosion problem is to use a pipe and fittings made of anon-reactive material, such as PVC or polyethylene. There have been several attempts over the years to build portable systems from the materials over the years. While such system can be an improvement over previous systems because of the savings in water and greater reliability and service afforded by such system, the more reliable they are, the less portable they are. The more portable they are, the greater tendency to leak and come apart as plastic materials tend to shrink with cold and expand with heat.
Possible solution to the labor and handling problem would be to provide machinery or technique to move or install the aluminum pipe without field labor. Pipe and cable plows are commonly used to install underground lines (See FIGS. 1a and 1b). Pulled by a tractor, this xe2x80x9cplowxe2x80x9d puts a previously glued pipeline, cable or similar conduit at a fairly precise depth. A machine built by Wm. Miller Co. of Brawley, Calif. (U.S. Pat. Nos. 4,553,900 and 4,897,910) is available to pull pipe out of the field joint by joint. This machine is not capable of installing pipe and works with a limited number of aluminum coupling styles. Techniques have been tried and proven such that aluminum pipe is dragged linearly from field to field. This technique is utilized exclusively when fields or pipe positions are in a straight line relative to the next position. Aluminum pipelines (laterals) can only bend 5xc2x0 per 30 or 40 foot section and are rigid. Shifting and mechanization techniques for aluminum pipe has been tried and failed as the pipe and joints are inflexible or come apart from the rigors of mechanical handling.
One possible solution to the labor, handling, leaking, flexibility problem; is to provide non-metallic sprinkler laterals with no coupling device (i.e. hose). There are systems of this type. Polyethylene and rubber hoses equipped with sprinkler outlets are commonly used outside of the United States on small fields and occasionally in the U.S. In the western United States a common length of sprinkler lateral is 1320xe2x80x2 (xc2xc mile) and sprinklers generally operate at 45 to 70 psi. the minimum diameter of pipe to accommodate the flows required to operate sprinklers for this length of run is generally accepted to be 3xe2x80x3. Hose, of rubber or polyethylene, in order to handle the pressure must have considerable wall thickness and is therefore, very heavy (2 lbs per foot for poly vs. 0.5 lbs. per foot for aluminum). Rubber hoses have proven prohibitively. Reels of hoses 2xe2x80x3 diameter or greater are difficult to handle and transport.
It therefore, would be advantageous to provide an irrigation system which exhibited the portability of aluminum pipe, the integrity of a hose, the application and uniformity of xe2x80x9crain on demandxe2x80x9d, the durability of modern plastic material, the multiple irrigation capability of a drip system, and finally a system which would allow multiple operations in the field and be installed and removed mechanically.
The invention provides a portable pipe irrigation system that is used primarily for temporary drip and sprinkler installations. The portable installation system includes a unique trailer that comprises a movable platform which simplifies installation and removal of the irrigation system. The trailer/work station is either self propelled or pulled by a tractor. A central portion of the trailer/work station is of a sufficient length to accommodate pipe of various lengths and cross sections, e.g. pipes that are 20, 30, or 40 feet in length. The width of the trailer is typically from six to twelve feet. The axles of the trailer can be independently operated such that the trailer can make tight turns, therefore the rear axle is capable of maintaining direction while the front axle turns, when the rear axle reaches turning point it is operated independently.
The central portion of the trailer/work station is referred to herein as the magazine. A work platform is located at either end of the magazine. These platforms allow workers to manipulate the pipe in the magazine and load the pipe into one of three installation chutes. The platforms also serve to store previously staged piping components.
Catwalks are located on one or both sides of the magazine. If pipe is being installed from one side of the magazine, then only one catwalk is provided; if pipe is being installed from both sides of the magazine, then two catwalks are provided. The catwalks allow workers to walk safely and freely along the side of the magazine.
The workers are responsible for assembling the pipe sections and placing them in position to be installed in the field (or to disassemble the pipe when it is removed from the field).
Three chutes or channels are located on either side of the platform at a comfortable work level, e.g. about waist level. Two chutes have moving belts to orient the pipe for assembly. The chutes or channels extend the length of the platform. A primary chute is located closest to the magazine and is fitted with a fixed stop on the front end and a pushing lever on the rear end. The second chute is filled with a rubberized belt which moves toward the from of the trailer/work station. The third chute has a belt which travels to the rear of the trailer and is equipped with tools to facilitate final assembly of the sprinkler catwalk. The three chutes define work areas where the pipe sections are assembled and disassembled. Oriented above the third chute and belt is a pneumatically or hydraulically operated plunger/press when activated pushes the pipe tight against the belt and therefore increases the speed of the pipe and facilitates the joining of the previously assembled pipe and the new joints.
At the rear of the trailer/platform are outriggers that assist in the accurate placement of pipe in the field.